If you haven't drawn before, It can take a good year of drawing every day to get your drawings to the point where they don't look like children's drek. Of course, it can take a quarter of that time depending on your desire, ability and imagination. Put simply, if you haven't drawn before you are going to stink at the beginning. Don't get discouraged and practice. Draw your favorite characters to start and progress from there.
Drawing Comis the Marvel Way was a nice starter before I sought out more formal instruction.